LinkModules.cpp revision 1f6efa3996dd1929fbc129203ce5009b620e6969
1//===- lib/Linker/LinkModules.cpp - Module Linker Implementation ----------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements the LLVM module linker. 11// 12// Specifically, this: 13// * Merges global variables between the two modules 14// * Uninit + Uninit = Init, Init + Uninit = Init, Init + Init = Error if != 15// * Merges functions between two modules 16// 17//===----------------------------------------------------------------------===// 18 19#include "llvm/Linker.h" 20#include "llvm/Constants.h" 21#include "llvm/DerivedTypes.h" 22#include "llvm/LLVMContext.h" 23#include "llvm/Module.h" 24#include "llvm/TypeSymbolTable.h" 25#include "llvm/ValueSymbolTable.h" 26#include "llvm/Instructions.h" 27#include "llvm/Assembly/Writer.h" 28#include "llvm/Support/Debug.h" 29#include "llvm/Support/ErrorHandling.h" 30#include "llvm/Support/raw_ostream.h" 31#include "llvm/Support/Path.h" 32#include "llvm/Transforms/Utils/ValueMapper.h" 33#include "llvm/ADT/DenseMap.h" 34using namespace llvm; 35 36// Error - Simple wrapper function to conditionally assign to E and return true. 37// This just makes error return conditions a little bit simpler... 38static inline bool Error(std::string *E, const Twine &Message) { 39 if (E) *E = Message.str(); 40 return true; 41} 42 43// Function: ResolveTypes() 44// 45// Description: 46// Attempt to link the two specified types together. 47// 48// Inputs: 49// DestTy - The type to which we wish to resolve. 50// SrcTy - The original type which we want to resolve. 51// 52// Outputs: 53// DestST - The symbol table in which the new type should be placed. 54// 55// Return value: 56// true - There is an error and the types cannot yet be linked. 57// false - No errors. 58// 59static bool ResolveTypes(const Type *DestTy, const Type *SrcTy) { 60 if (DestTy == SrcTy) return false; // If already equal, noop 61 assert(DestTy && SrcTy && "Can't handle null types"); 62 63 if (const OpaqueType *OT = dyn_cast<OpaqueType>(DestTy)) { 64 // Type _is_ in module, just opaque... 65 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(SrcTy); 66 } else if (const OpaqueType *OT = dyn_cast<OpaqueType>(SrcTy)) { 67 const_cast<OpaqueType*>(OT)->refineAbstractTypeTo(DestTy); 68 } else { 69 return true; // Cannot link types... not-equal and neither is opaque. 70 } 71 return false; 72} 73 74/// LinkerTypeMap - This implements a map of types that is stable 75/// even if types are resolved/refined to other types. This is not a general 76/// purpose map, it is specific to the linker's use. 77namespace { 78class LinkerTypeMap : public AbstractTypeUser { 79 typedef DenseMap<const Type*, PATypeHolder> TheMapTy; 80 TheMapTy TheMap; 81 82 LinkerTypeMap(const LinkerTypeMap&); // DO NOT IMPLEMENT 83 void operator=(const LinkerTypeMap&); // DO NOT IMPLEMENT 84public: 85 LinkerTypeMap() {} 86 ~LinkerTypeMap() { 87 for (DenseMap<const Type*, PATypeHolder>::iterator I = TheMap.begin(), 88 E = TheMap.end(); I != E; ++I) 89 I->first->removeAbstractTypeUser(this); 90 } 91 92 /// lookup - Return the value for the specified type or null if it doesn't 93 /// exist. 94 const Type *lookup(const Type *Ty) const { 95 TheMapTy::const_iterator I = TheMap.find(Ty); 96 if (I != TheMap.end()) return I->second; 97 return 0; 98 } 99 100 /// insert - This returns true if the pointer was new to the set, false if it 101 /// was already in the set. 102 bool insert(const Type *Src, const Type *Dst) { 103 if (!TheMap.insert(std::make_pair(Src, PATypeHolder(Dst))).second) 104 return false; // Already in map. 105 if (Src->isAbstract()) 106 Src->addAbstractTypeUser(this); 107 return true; 108 } 109 110protected: 111 /// refineAbstractType - The callback method invoked when an abstract type is 112 /// resolved to another type. An object must override this method to update 113 /// its internal state to reference NewType instead of OldType. 114 /// 115 virtual void refineAbstractType(const DerivedType *OldTy, 116 const Type *NewTy) { 117 TheMapTy::iterator I = TheMap.find(OldTy); 118 const Type *DstTy = I->second; 119 120 TheMap.erase(I); 121 if (OldTy->isAbstract()) 122 OldTy->removeAbstractTypeUser(this); 123 124 // Don't reinsert into the map if the key is concrete now. 125 if (NewTy->isAbstract()) 126 insert(NewTy, DstTy); 127 } 128 129 /// The other case which AbstractTypeUsers must be aware of is when a type 130 /// makes the transition from being abstract (where it has clients on it's 131 /// AbstractTypeUsers list) to concrete (where it does not). This method 132 /// notifies ATU's when this occurs for a type. 133 virtual void typeBecameConcrete(const DerivedType *AbsTy) { 134 TheMap.erase(AbsTy); 135 AbsTy->removeAbstractTypeUser(this); 136 } 137 138 // for debugging... 139 virtual void dump() const { 140 dbgs() << "AbstractTypeSet!\n"; 141 } 142}; 143} 144 145 146// RecursiveResolveTypes - This is just like ResolveTypes, except that it 147// recurses down into derived types, merging the used types if the parent types 148// are compatible. 149static bool RecursiveResolveTypesI(const Type *DstTy, const Type *SrcTy, 150 LinkerTypeMap &Pointers) { 151 if (DstTy == SrcTy) return false; // If already equal, noop 152 153 // If we found our opaque type, resolve it now! 154 if (DstTy->isOpaqueTy() || SrcTy->isOpaqueTy()) 155 return ResolveTypes(DstTy, SrcTy); 156 157 // Two types cannot be resolved together if they are of different primitive 158 // type. For example, we cannot resolve an int to a float. 159 if (DstTy->getTypeID() != SrcTy->getTypeID()) return true; 160 161 // If neither type is abstract, then they really are just different types. 162 if (!DstTy->isAbstract() && !SrcTy->isAbstract()) 163 return true; 164 165 // Otherwise, resolve the used type used by this derived type... 166 switch (DstTy->getTypeID()) { 167 default: 168 return true; 169 case Type::FunctionTyID: { 170 const FunctionType *DstFT = cast<FunctionType>(DstTy); 171 const FunctionType *SrcFT = cast<FunctionType>(SrcTy); 172 if (DstFT->isVarArg() != SrcFT->isVarArg() || 173 DstFT->getNumContainedTypes() != SrcFT->getNumContainedTypes()) 174 return true; 175 176 // Use TypeHolder's so recursive resolution won't break us. 177 PATypeHolder ST(SrcFT), DT(DstFT); 178 for (unsigned i = 0, e = DstFT->getNumContainedTypes(); i != e; ++i) { 179 const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i); 180 if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers)) 181 return true; 182 } 183 return false; 184 } 185 case Type::StructTyID: { 186 const StructType *DstST = cast<StructType>(DstTy); 187 const StructType *SrcST = cast<StructType>(SrcTy); 188 if (DstST->getNumContainedTypes() != SrcST->getNumContainedTypes()) 189 return true; 190 191 PATypeHolder ST(SrcST), DT(DstST); 192 for (unsigned i = 0, e = DstST->getNumContainedTypes(); i != e; ++i) { 193 const Type *SE = ST->getContainedType(i), *DE = DT->getContainedType(i); 194 if (SE != DE && RecursiveResolveTypesI(DE, SE, Pointers)) 195 return true; 196 } 197 return false; 198 } 199 case Type::ArrayTyID: { 200 const ArrayType *DAT = cast<ArrayType>(DstTy); 201 const ArrayType *SAT = cast<ArrayType>(SrcTy); 202 if (DAT->getNumElements() != SAT->getNumElements()) return true; 203 return RecursiveResolveTypesI(DAT->getElementType(), SAT->getElementType(), 204 Pointers); 205 } 206 case Type::VectorTyID: { 207 const VectorType *DVT = cast<VectorType>(DstTy); 208 const VectorType *SVT = cast<VectorType>(SrcTy); 209 if (DVT->getNumElements() != SVT->getNumElements()) return true; 210 return RecursiveResolveTypesI(DVT->getElementType(), SVT->getElementType(), 211 Pointers); 212 } 213 case Type::PointerTyID: { 214 const PointerType *DstPT = cast<PointerType>(DstTy); 215 const PointerType *SrcPT = cast<PointerType>(SrcTy); 216 217 if (DstPT->getAddressSpace() != SrcPT->getAddressSpace()) 218 return true; 219 220 // If this is a pointer type, check to see if we have already seen it. If 221 // so, we are in a recursive branch. Cut off the search now. We cannot use 222 // an associative container for this search, because the type pointers (keys 223 // in the container) change whenever types get resolved. 224 if (SrcPT->isAbstract()) 225 if (const Type *ExistingDestTy = Pointers.lookup(SrcPT)) 226 return ExistingDestTy != DstPT; 227 228 if (DstPT->isAbstract()) 229 if (const Type *ExistingSrcTy = Pointers.lookup(DstPT)) 230 return ExistingSrcTy != SrcPT; 231 // Otherwise, add the current pointers to the vector to stop recursion on 232 // this pair. 233 if (DstPT->isAbstract()) 234 Pointers.insert(DstPT, SrcPT); 235 if (SrcPT->isAbstract()) 236 Pointers.insert(SrcPT, DstPT); 237 238 return RecursiveResolveTypesI(DstPT->getElementType(), 239 SrcPT->getElementType(), Pointers); 240 } 241 } 242} 243 244static bool RecursiveResolveTypes(const Type *DestTy, const Type *SrcTy) { 245 LinkerTypeMap PointerTypes; 246 return RecursiveResolveTypesI(DestTy, SrcTy, PointerTypes); 247} 248 249 250// LinkTypes - Go through the symbol table of the Src module and see if any 251// types are named in the src module that are not named in the Dst module. 252// Make sure there are no type name conflicts. 253static bool LinkTypes(Module *Dest, const Module *Src, std::string *Err) { 254 TypeSymbolTable *DestST = &Dest->getTypeSymbolTable(); 255 const TypeSymbolTable *SrcST = &Src->getTypeSymbolTable(); 256 257 // Look for a type plane for Type's... 258 TypeSymbolTable::const_iterator TI = SrcST->begin(); 259 TypeSymbolTable::const_iterator TE = SrcST->end(); 260 if (TI == TE) return false; // No named types, do nothing. 261 262 // Some types cannot be resolved immediately because they depend on other 263 // types being resolved to each other first. This contains a list of types we 264 // are waiting to recheck. 265 std::vector<std::string> DelayedTypesToResolve; 266 267 for ( ; TI != TE; ++TI ) { 268 const std::string &Name = TI->first; 269 const Type *RHS = TI->second; 270 271 // Check to see if this type name is already in the dest module. 272 Type *Entry = DestST->lookup(Name); 273 274 // If the name is just in the source module, bring it over to the dest. 275 if (Entry == 0) { 276 if (!Name.empty()) 277 DestST->insert(Name, const_cast<Type*>(RHS)); 278 } else if (ResolveTypes(Entry, RHS)) { 279 // They look different, save the types 'till later to resolve. 280 DelayedTypesToResolve.push_back(Name); 281 } 282 } 283 284 // Iteratively resolve types while we can... 285 while (!DelayedTypesToResolve.empty()) { 286 // Loop over all of the types, attempting to resolve them if possible... 287 unsigned OldSize = DelayedTypesToResolve.size(); 288 289 // Try direct resolution by name... 290 for (unsigned i = 0; i != DelayedTypesToResolve.size(); ++i) { 291 const std::string &Name = DelayedTypesToResolve[i]; 292 Type *T1 = SrcST->lookup(Name); 293 Type *T2 = DestST->lookup(Name); 294 if (!ResolveTypes(T2, T1)) { 295 // We are making progress! 296 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i); 297 --i; 298 } 299 } 300 301 // Did we not eliminate any types? 302 if (DelayedTypesToResolve.size() == OldSize) { 303 // Attempt to resolve subelements of types. This allows us to merge these 304 // two types: { int* } and { opaque* } 305 for (unsigned i = 0, e = DelayedTypesToResolve.size(); i != e; ++i) { 306 const std::string &Name = DelayedTypesToResolve[i]; 307 if (!RecursiveResolveTypes(SrcST->lookup(Name), DestST->lookup(Name))) { 308 // We are making progress! 309 DelayedTypesToResolve.erase(DelayedTypesToResolve.begin()+i); 310 311 // Go back to the main loop, perhaps we can resolve directly by name 312 // now... 313 break; 314 } 315 } 316 317 // If we STILL cannot resolve the types, then there is something wrong. 318 if (DelayedTypesToResolve.size() == OldSize) { 319 // Remove the symbol name from the destination. 320 DelayedTypesToResolve.pop_back(); 321 } 322 } 323 } 324 325 326 return false; 327} 328 329/// ForceRenaming - The LLVM SymbolTable class autorenames globals that conflict 330/// in the symbol table. This is good for all clients except for us. Go 331/// through the trouble to force this back. 332static void ForceRenaming(GlobalValue *GV, const std::string &Name) { 333 assert(GV->getName() != Name && "Can't force rename to self"); 334 ValueSymbolTable &ST = GV->getParent()->getValueSymbolTable(); 335 336 // If there is a conflict, rename the conflict. 337 if (GlobalValue *ConflictGV = cast_or_null<GlobalValue>(ST.lookup(Name))) { 338 assert(ConflictGV->hasLocalLinkage() && 339 "Not conflicting with a static global, should link instead!"); 340 GV->takeName(ConflictGV); 341 ConflictGV->setName(Name); // This will cause ConflictGV to get renamed 342 assert(ConflictGV->getName() != Name && "ForceRenaming didn't work"); 343 } else { 344 GV->setName(Name); // Force the name back 345 } 346} 347 348/// CopyGVAttributes - copy additional attributes (those not needed to construct 349/// a GlobalValue) from the SrcGV to the DestGV. 350static void CopyGVAttributes(GlobalValue *DestGV, const GlobalValue *SrcGV) { 351 // Use the maximum alignment, rather than just copying the alignment of SrcGV. 352 unsigned Alignment = std::max(DestGV->getAlignment(), SrcGV->getAlignment()); 353 DestGV->copyAttributesFrom(SrcGV); 354 DestGV->setAlignment(Alignment); 355} 356 357/// GetLinkageResult - This analyzes the two global values and determines what 358/// the result will look like in the destination module. In particular, it 359/// computes the resultant linkage type, computes whether the global in the 360/// source should be copied over to the destination (replacing the existing 361/// one), and computes whether this linkage is an error or not. It also performs 362/// visibility checks: we cannot link together two symbols with different 363/// visibilities. 364static bool GetLinkageResult(GlobalValue *Dest, const GlobalValue *Src, 365 GlobalValue::LinkageTypes <, bool &LinkFromSrc, 366 std::string *Err) { 367 assert((!Dest || !Src->hasLocalLinkage()) && 368 "If Src has internal linkage, Dest shouldn't be set!"); 369 if (!Dest) { 370 // Linking something to nothing. 371 LinkFromSrc = true; 372 LT = Src->getLinkage(); 373 } else if (Src->isDeclaration()) { 374 // If Src is external or if both Src & Dest are external.. Just link the 375 // external globals, we aren't adding anything. 376 if (Src->hasDLLImportLinkage()) { 377 // If one of GVs has DLLImport linkage, result should be dllimport'ed. 378 if (Dest->isDeclaration()) { 379 LinkFromSrc = true; 380 LT = Src->getLinkage(); 381 } 382 } else if (Dest->hasExternalWeakLinkage()) { 383 // If the Dest is weak, use the source linkage. 384 LinkFromSrc = true; 385 LT = Src->getLinkage(); 386 } else { 387 LinkFromSrc = false; 388 LT = Dest->getLinkage(); 389 } 390 } else if (Dest->isDeclaration() && !Dest->hasDLLImportLinkage()) { 391 // If Dest is external but Src is not: 392 LinkFromSrc = true; 393 LT = Src->getLinkage(); 394 } else if (Src->hasAppendingLinkage() || Dest->hasAppendingLinkage()) { 395 if (Src->getLinkage() != Dest->getLinkage()) 396 return Error(Err, "Linking globals named '" + Src->getName() + 397 "': can only link appending global with another appending global!"); 398 LinkFromSrc = true; // Special cased. 399 LT = Src->getLinkage(); 400 } else if (Src->isWeakForLinker()) { 401 // At this point we know that Dest has LinkOnce, External*, Weak, Common, 402 // or DLL* linkage. 403 if (Dest->hasExternalWeakLinkage() || 404 Dest->hasAvailableExternallyLinkage() || 405 (Dest->hasLinkOnceLinkage() && 406 (Src->hasWeakLinkage() || Src->hasCommonLinkage()))) { 407 LinkFromSrc = true; 408 LT = Src->getLinkage(); 409 } else { 410 LinkFromSrc = false; 411 LT = Dest->getLinkage(); 412 } 413 } else if (Dest->isWeakForLinker()) { 414 // At this point we know that Src has External* or DLL* linkage. 415 if (Src->hasExternalWeakLinkage()) { 416 LinkFromSrc = false; 417 LT = Dest->getLinkage(); 418 } else { 419 LinkFromSrc = true; 420 LT = GlobalValue::ExternalLinkage; 421 } 422 } else { 423 assert((Dest->hasExternalLinkage() || 424 Dest->hasDLLImportLinkage() || 425 Dest->hasDLLExportLinkage() || 426 Dest->hasExternalWeakLinkage()) && 427 (Src->hasExternalLinkage() || 428 Src->hasDLLImportLinkage() || 429 Src->hasDLLExportLinkage() || 430 Src->hasExternalWeakLinkage()) && 431 "Unexpected linkage type!"); 432 return Error(Err, "Linking globals named '" + Src->getName() + 433 "': symbol multiply defined!"); 434 } 435 436 // Check visibility 437 if (Dest && Src->getVisibility() != Dest->getVisibility()) 438 if (!Src->isDeclaration() && !Dest->isDeclaration()) 439 return Error(Err, "Linking globals named '" + Src->getName() + 440 "': symbols have different visibilities!"); 441 return false; 442} 443 444// Insert all of the named mdnoes in Src into the Dest module. 445static void LinkNamedMDNodes(Module *Dest, Module *Src, 446 ValueToValueMapTy &ValueMap) { 447 for (Module::const_named_metadata_iterator I = Src->named_metadata_begin(), 448 E = Src->named_metadata_end(); I != E; ++I) { 449 const NamedMDNode *SrcNMD = I; 450 NamedMDNode *DestNMD = Dest->getOrInsertNamedMetadata(SrcNMD->getName()); 451 // Add Src elements into Dest node. 452 for (unsigned i = 0, e = SrcNMD->getNumOperands(); i != e; ++i) 453 DestNMD->addOperand(cast<MDNode>(MapValue(SrcNMD->getOperand(i), 454 ValueMap, 455 true))); 456 } 457} 458 459// LinkGlobals - Loop through the global variables in the src module and merge 460// them into the dest module. 461static bool LinkGlobals(Module *Dest, const Module *Src, 462 ValueToValueMapTy &ValueMap, 463 std::multimap<std::string, GlobalVariable *> &AppendingVars, 464 std::string *Err) { 465 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); 466 467 // Loop over all of the globals in the src module, mapping them over as we go 468 for (Module::const_global_iterator I = Src->global_begin(), 469 E = Src->global_end(); I != E; ++I) { 470 const GlobalVariable *SGV = I; 471 GlobalValue *DGV = 0; 472 473 // Check to see if may have to link the global with the global, alias or 474 // function. 475 if (SGV->hasName() && !SGV->hasLocalLinkage()) 476 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SGV->getName())); 477 478 // If we found a global with the same name in the dest module, but it has 479 // internal linkage, we are really not doing any linkage here. 480 if (DGV && DGV->hasLocalLinkage()) 481 DGV = 0; 482 483 // If types don't agree due to opaque types, try to resolve them. 484 if (DGV && DGV->getType() != SGV->getType()) 485 RecursiveResolveTypes(SGV->getType(), DGV->getType()); 486 487 assert((SGV->hasInitializer() || SGV->hasExternalWeakLinkage() || 488 SGV->hasExternalLinkage() || SGV->hasDLLImportLinkage()) && 489 "Global must either be external or have an initializer!"); 490 491 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 492 bool LinkFromSrc = false; 493 if (GetLinkageResult(DGV, SGV, NewLinkage, LinkFromSrc, Err)) 494 return true; 495 496 if (DGV == 0) { 497 // No linking to be performed, simply create an identical version of the 498 // symbol over in the dest module... the initializer will be filled in 499 // later by LinkGlobalInits. 500 GlobalVariable *NewDGV = 501 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 502 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 503 SGV->getName(), 0, false, 504 SGV->getType()->getAddressSpace()); 505 // Propagate alignment, visibility and section info. 506 CopyGVAttributes(NewDGV, SGV); 507 508 // If the LLVM runtime renamed the global, but it is an externally visible 509 // symbol, DGV must be an existing global with internal linkage. Rename 510 // it. 511 if (!NewDGV->hasLocalLinkage() && NewDGV->getName() != SGV->getName()) 512 ForceRenaming(NewDGV, SGV->getName()); 513 514 // Make sure to remember this mapping. 515 ValueMap[SGV] = NewDGV; 516 517 // Keep track that this is an appending variable. 518 if (SGV->hasAppendingLinkage()) 519 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 520 continue; 521 } 522 523 // If the visibilities of the symbols disagree and the destination is a 524 // prototype, take the visibility of its input. 525 if (DGV->isDeclaration()) 526 DGV->setVisibility(SGV->getVisibility()); 527 528 if (DGV->hasAppendingLinkage()) { 529 // No linking is performed yet. Just insert a new copy of the global, and 530 // keep track of the fact that it is an appending variable in the 531 // AppendingVars map. The name is cleared out so that no linkage is 532 // performed. 533 GlobalVariable *NewDGV = 534 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 535 SGV->isConstant(), SGV->getLinkage(), /*init*/0, 536 "", 0, false, 537 SGV->getType()->getAddressSpace()); 538 539 // Set alignment allowing CopyGVAttributes merge it with alignment of SGV. 540 NewDGV->setAlignment(DGV->getAlignment()); 541 // Propagate alignment, section and visibility info. 542 CopyGVAttributes(NewDGV, SGV); 543 544 // Make sure to remember this mapping... 545 ValueMap[SGV] = NewDGV; 546 547 // Keep track that this is an appending variable... 548 AppendingVars.insert(std::make_pair(SGV->getName(), NewDGV)); 549 continue; 550 } 551 552 if (LinkFromSrc) { 553 if (isa<GlobalAlias>(DGV)) 554 return Error(Err, "Global-Alias Collision on '" + SGV->getName() + 555 "': symbol multiple defined"); 556 557 // If the types don't match, and if we are to link from the source, nuke 558 // DGV and create a new one of the appropriate type. Note that the thing 559 // we are replacing may be a function (if a prototype, weak, etc) or a 560 // global variable. 561 GlobalVariable *NewDGV = 562 new GlobalVariable(*Dest, SGV->getType()->getElementType(), 563 SGV->isConstant(), NewLinkage, /*init*/0, 564 DGV->getName(), 0, false, 565 SGV->getType()->getAddressSpace()); 566 567 // Propagate alignment, section, and visibility info. 568 CopyGVAttributes(NewDGV, SGV); 569 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDGV, 570 DGV->getType())); 571 572 // DGV will conflict with NewDGV because they both had the same 573 // name. We must erase this now so ForceRenaming doesn't assert 574 // because DGV might not have internal linkage. 575 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV)) 576 Var->eraseFromParent(); 577 else 578 cast<Function>(DGV)->eraseFromParent(); 579 580 // If the symbol table renamed the global, but it is an externally visible 581 // symbol, DGV must be an existing global with internal linkage. Rename. 582 if (NewDGV->getName() != SGV->getName() && !NewDGV->hasLocalLinkage()) 583 ForceRenaming(NewDGV, SGV->getName()); 584 585 // Inherit const as appropriate. 586 NewDGV->setConstant(SGV->isConstant()); 587 588 // Make sure to remember this mapping. 589 ValueMap[SGV] = NewDGV; 590 continue; 591 } 592 593 // Not "link from source", keep the one in the DestModule and remap the 594 // input onto it. 595 596 // Special case for const propagation. 597 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) 598 if (DGVar->isDeclaration() && SGV->isConstant() && !DGVar->isConstant()) 599 DGVar->setConstant(true); 600 601 // SGV is global, but DGV is alias. 602 if (isa<GlobalAlias>(DGV)) { 603 // The only valid mappings are: 604 // - SGV is external declaration, which is effectively a no-op. 605 // - SGV is weak, when we just need to throw SGV out. 606 if (!SGV->isDeclaration() && !SGV->isWeakForLinker()) 607 return Error(Err, "Global-Alias Collision on '" + SGV->getName() + 608 "': symbol multiple defined"); 609 } 610 611 // Set calculated linkage 612 DGV->setLinkage(NewLinkage); 613 614 // Make sure to remember this mapping... 615 ValueMap[SGV] = ConstantExpr::getBitCast(DGV, SGV->getType()); 616 } 617 return false; 618} 619 620static GlobalValue::LinkageTypes 621CalculateAliasLinkage(const GlobalValue *SGV, const GlobalValue *DGV) { 622 GlobalValue::LinkageTypes SL = SGV->getLinkage(); 623 GlobalValue::LinkageTypes DL = DGV->getLinkage(); 624 if (SL == GlobalValue::ExternalLinkage || DL == GlobalValue::ExternalLinkage) 625 return GlobalValue::ExternalLinkage; 626 else if (SL == GlobalValue::WeakAnyLinkage || 627 DL == GlobalValue::WeakAnyLinkage) 628 return GlobalValue::WeakAnyLinkage; 629 else if (SL == GlobalValue::WeakODRLinkage || 630 DL == GlobalValue::WeakODRLinkage) 631 return GlobalValue::WeakODRLinkage; 632 else if (SL == GlobalValue::InternalLinkage && 633 DL == GlobalValue::InternalLinkage) 634 return GlobalValue::InternalLinkage; 635 else if (SL == GlobalValue::LinkerPrivateLinkage && 636 DL == GlobalValue::LinkerPrivateLinkage) 637 return GlobalValue::LinkerPrivateLinkage; 638 else if (SL == GlobalValue::LinkerPrivateWeakLinkage && 639 DL == GlobalValue::LinkerPrivateWeakLinkage) 640 return GlobalValue::LinkerPrivateWeakLinkage; 641 else if (SL == GlobalValue::LinkerPrivateWeakDefAutoLinkage && 642 DL == GlobalValue::LinkerPrivateWeakDefAutoLinkage) 643 return GlobalValue::LinkerPrivateWeakDefAutoLinkage; 644 else { 645 assert (SL == GlobalValue::PrivateLinkage && 646 DL == GlobalValue::PrivateLinkage && "Unexpected linkage type"); 647 return GlobalValue::PrivateLinkage; 648 } 649} 650 651// LinkAlias - Loop through the alias in the src module and link them into the 652// dest module. We're assuming, that all functions/global variables were already 653// linked in. 654static bool LinkAlias(Module *Dest, const Module *Src, 655 ValueToValueMapTy &ValueMap, 656 std::string *Err) { 657 // Loop over all alias in the src module 658 for (Module::const_alias_iterator I = Src->alias_begin(), 659 E = Src->alias_end(); I != E; ++I) { 660 const GlobalAlias *SGA = I; 661 const GlobalValue *SAliasee = SGA->getAliasedGlobal(); 662 GlobalAlias *NewGA = NULL; 663 664 // Globals were already linked, thus we can just query ValueMap for variant 665 // of SAliasee in Dest. 666 ValueToValueMapTy::const_iterator VMI = ValueMap.find(SAliasee); 667 assert(VMI != ValueMap.end() && "Aliasee not linked"); 668 GlobalValue* DAliasee = cast<GlobalValue>(VMI->second); 669 GlobalValue* DGV = NULL; 670 671 // Fixup aliases to bitcasts. Note that aliases to GEPs are still broken 672 // by this, but aliases to GEPs are broken to a lot of other things, so 673 // it's less important. 674 Constant *DAliaseeConst = DAliasee; 675 if (SGA->getType() != DAliasee->getType()) 676 DAliaseeConst = ConstantExpr::getBitCast(DAliasee, SGA->getType()); 677 678 // Try to find something 'similar' to SGA in destination module. 679 if (!DGV && !SGA->hasLocalLinkage()) { 680 DGV = Dest->getNamedAlias(SGA->getName()); 681 682 // If types don't agree due to opaque types, try to resolve them. 683 if (DGV && DGV->getType() != SGA->getType()) 684 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 685 } 686 687 if (!DGV && !SGA->hasLocalLinkage()) { 688 DGV = Dest->getGlobalVariable(SGA->getName()); 689 690 // If types don't agree due to opaque types, try to resolve them. 691 if (DGV && DGV->getType() != SGA->getType()) 692 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 693 } 694 695 if (!DGV && !SGA->hasLocalLinkage()) { 696 DGV = Dest->getFunction(SGA->getName()); 697 698 // If types don't agree due to opaque types, try to resolve them. 699 if (DGV && DGV->getType() != SGA->getType()) 700 RecursiveResolveTypes(SGA->getType(), DGV->getType()); 701 } 702 703 // No linking to be performed on internal stuff. 704 if (DGV && DGV->hasLocalLinkage()) 705 DGV = NULL; 706 707 if (GlobalAlias *DGA = dyn_cast_or_null<GlobalAlias>(DGV)) { 708 // Types are known to be the same, check whether aliasees equal. As 709 // globals are already linked we just need query ValueMap to find the 710 // mapping. 711 if (DAliasee == DGA->getAliasedGlobal()) { 712 // This is just two copies of the same alias. Propagate linkage, if 713 // necessary. 714 DGA->setLinkage(CalculateAliasLinkage(SGA, DGA)); 715 716 NewGA = DGA; 717 // Proceed to 'common' steps 718 } else 719 return Error(Err, "Alias Collision on '" + SGA->getName()+ 720 "': aliases have different aliasees"); 721 } else if (GlobalVariable *DGVar = dyn_cast_or_null<GlobalVariable>(DGV)) { 722 // The only allowed way is to link alias with external declaration or weak 723 // symbol.. 724 if (DGVar->isDeclaration() || DGVar->isWeakForLinker()) { 725 // But only if aliasee is global too... 726 if (!isa<GlobalVariable>(DAliasee)) 727 return Error(Err, "Global-Alias Collision on '" + SGA->getName() + 728 "': aliasee is not global variable"); 729 730 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 731 SGA->getName(), DAliaseeConst, Dest); 732 CopyGVAttributes(NewGA, SGA); 733 734 // Any uses of DGV need to change to NewGA, with cast, if needed. 735 if (SGA->getType() != DGVar->getType()) 736 DGVar->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA, 737 DGVar->getType())); 738 else 739 DGVar->replaceAllUsesWith(NewGA); 740 741 // DGVar will conflict with NewGA because they both had the same 742 // name. We must erase this now so ForceRenaming doesn't assert 743 // because DGV might not have internal linkage. 744 DGVar->eraseFromParent(); 745 746 // Proceed to 'common' steps 747 } else 748 return Error(Err, "Global-Alias Collision on '" + SGA->getName() + 749 "': symbol multiple defined"); 750 } else if (Function *DF = dyn_cast_or_null<Function>(DGV)) { 751 // The only allowed way is to link alias with external declaration or weak 752 // symbol... 753 if (DF->isDeclaration() || DF->isWeakForLinker()) { 754 // But only if aliasee is function too... 755 if (!isa<Function>(DAliasee)) 756 return Error(Err, "Function-Alias Collision on '" + SGA->getName() + 757 "': aliasee is not function"); 758 759 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 760 SGA->getName(), DAliaseeConst, Dest); 761 CopyGVAttributes(NewGA, SGA); 762 763 // Any uses of DF need to change to NewGA, with cast, if needed. 764 if (SGA->getType() != DF->getType()) 765 DF->replaceAllUsesWith(ConstantExpr::getBitCast(NewGA, 766 DF->getType())); 767 else 768 DF->replaceAllUsesWith(NewGA); 769 770 // DF will conflict with NewGA because they both had the same 771 // name. We must erase this now so ForceRenaming doesn't assert 772 // because DF might not have internal linkage. 773 DF->eraseFromParent(); 774 775 // Proceed to 'common' steps 776 } else 777 return Error(Err, "Function-Alias Collision on '" + SGA->getName() + 778 "': symbol multiple defined"); 779 } else { 780 // No linking to be performed, simply create an identical version of the 781 // alias over in the dest module... 782 NewGA = new GlobalAlias(SGA->getType(), SGA->getLinkage(), 783 SGA->getName(), DAliaseeConst, Dest); 784 CopyGVAttributes(NewGA, SGA); 785 786 // Proceed to 'common' steps 787 } 788 789 assert(NewGA && "No alias was created in destination module!"); 790 791 // If the symbol table renamed the alias, but it is an externally visible 792 // symbol, DGA must be an global value with internal linkage. Rename it. 793 if (NewGA->getName() != SGA->getName() && 794 !NewGA->hasLocalLinkage()) 795 ForceRenaming(NewGA, SGA->getName()); 796 797 // Remember this mapping so uses in the source module get remapped 798 // later by MapValue. 799 ValueMap[SGA] = NewGA; 800 } 801 802 return false; 803} 804 805 806// LinkGlobalInits - Update the initializers in the Dest module now that all 807// globals that may be referenced are in Dest. 808static bool LinkGlobalInits(Module *Dest, const Module *Src, 809 ValueToValueMapTy &ValueMap, 810 std::string *Err) { 811 // Loop over all of the globals in the src module, mapping them over as we go 812 for (Module::const_global_iterator I = Src->global_begin(), 813 E = Src->global_end(); I != E; ++I) { 814 const GlobalVariable *SGV = I; 815 816 if (SGV->hasInitializer()) { // Only process initialized GV's 817 // Figure out what the initializer looks like in the dest module... 818 Constant *SInit = 819 cast<Constant>(MapValue(SGV->getInitializer(), ValueMap, true)); 820 // Grab destination global variable or alias. 821 GlobalValue *DGV = cast<GlobalValue>(ValueMap[SGV]->stripPointerCasts()); 822 823 // If dest if global variable, check that initializers match. 824 if (GlobalVariable *DGVar = dyn_cast<GlobalVariable>(DGV)) { 825 if (DGVar->hasInitializer()) { 826 if (SGV->hasExternalLinkage()) { 827 if (DGVar->getInitializer() != SInit) 828 return Error(Err, "Global Variable Collision on '" + 829 SGV->getName() + 830 "': global variables have different initializers"); 831 } else if (DGVar->isWeakForLinker()) { 832 // Nothing is required, mapped values will take the new global 833 // automatically. 834 } else if (SGV->isWeakForLinker()) { 835 // Nothing is required, mapped values will take the new global 836 // automatically. 837 } else if (DGVar->hasAppendingLinkage()) { 838 llvm_unreachable("Appending linkage unimplemented!"); 839 } else { 840 llvm_unreachable("Unknown linkage!"); 841 } 842 } else { 843 // Copy the initializer over now... 844 DGVar->setInitializer(SInit); 845 } 846 } else { 847 // Destination is alias, the only valid situation is when source is 848 // weak. Also, note, that we already checked linkage in LinkGlobals(), 849 // thus we assert here. 850 // FIXME: Should we weaken this assumption, 'dereference' alias and 851 // check for initializer of aliasee? 852 assert(SGV->isWeakForLinker()); 853 } 854 } 855 } 856 return false; 857} 858 859// LinkFunctionProtos - Link the functions together between the two modules, 860// without doing function bodies... this just adds external function prototypes 861// to the Dest function... 862// 863static bool LinkFunctionProtos(Module *Dest, const Module *Src, 864 ValueToValueMapTy &ValueMap, 865 std::string *Err) { 866 ValueSymbolTable &DestSymTab = Dest->getValueSymbolTable(); 867 868 // Loop over all of the functions in the src module, mapping them over 869 for (Module::const_iterator I = Src->begin(), E = Src->end(); I != E; ++I) { 870 const Function *SF = I; // SrcFunction 871 GlobalValue *DGV = 0; 872 873 // Check to see if may have to link the function with the global, alias or 874 // function. 875 if (SF->hasName() && !SF->hasLocalLinkage()) 876 DGV = cast_or_null<GlobalValue>(DestSymTab.lookup(SF->getName())); 877 878 // If we found a global with the same name in the dest module, but it has 879 // internal linkage, we are really not doing any linkage here. 880 if (DGV && DGV->hasLocalLinkage()) 881 DGV = 0; 882 883 // If types don't agree due to opaque types, try to resolve them. 884 if (DGV && DGV->getType() != SF->getType()) 885 RecursiveResolveTypes(SF->getType(), DGV->getType()); 886 887 GlobalValue::LinkageTypes NewLinkage = GlobalValue::InternalLinkage; 888 bool LinkFromSrc = false; 889 if (GetLinkageResult(DGV, SF, NewLinkage, LinkFromSrc, Err)) 890 return true; 891 892 // If there is no linkage to be performed, just bring over SF without 893 // modifying it. 894 if (DGV == 0) { 895 // Function does not already exist, simply insert an function signature 896 // identical to SF into the dest module. 897 Function *NewDF = Function::Create(SF->getFunctionType(), 898 SF->getLinkage(), 899 SF->getName(), Dest); 900 CopyGVAttributes(NewDF, SF); 901 902 // If the LLVM runtime renamed the function, but it is an externally 903 // visible symbol, DF must be an existing function with internal linkage. 904 // Rename it. 905 if (!NewDF->hasLocalLinkage() && NewDF->getName() != SF->getName()) 906 ForceRenaming(NewDF, SF->getName()); 907 908 // ... and remember this mapping... 909 ValueMap[SF] = NewDF; 910 continue; 911 } 912 913 // If the visibilities of the symbols disagree and the destination is a 914 // prototype, take the visibility of its input. 915 if (DGV->isDeclaration()) 916 DGV->setVisibility(SF->getVisibility()); 917 918 if (LinkFromSrc) { 919 if (isa<GlobalAlias>(DGV)) 920 return Error(Err, "Function-Alias Collision on '" + SF->getName() + 921 "': symbol multiple defined"); 922 923 // We have a definition of the same name but different type in the 924 // source module. Copy the prototype to the destination and replace 925 // uses of the destination's prototype with the new prototype. 926 Function *NewDF = Function::Create(SF->getFunctionType(), NewLinkage, 927 SF->getName(), Dest); 928 CopyGVAttributes(NewDF, SF); 929 930 // Any uses of DF need to change to NewDF, with cast 931 DGV->replaceAllUsesWith(ConstantExpr::getBitCast(NewDF, 932 DGV->getType())); 933 934 // DF will conflict with NewDF because they both had the same. We must 935 // erase this now so ForceRenaming doesn't assert because DF might 936 // not have internal linkage. 937 if (GlobalVariable *Var = dyn_cast<GlobalVariable>(DGV)) 938 Var->eraseFromParent(); 939 else 940 cast<Function>(DGV)->eraseFromParent(); 941 942 // If the symbol table renamed the function, but it is an externally 943 // visible symbol, DF must be an existing function with internal 944 // linkage. Rename it. 945 if (NewDF->getName() != SF->getName() && !NewDF->hasLocalLinkage()) 946 ForceRenaming(NewDF, SF->getName()); 947 948 // Remember this mapping so uses in the source module get remapped 949 // later by MapValue. 950 ValueMap[SF] = NewDF; 951 continue; 952 } 953 954 // Not "link from source", keep the one in the DestModule and remap the 955 // input onto it. 956 957 if (isa<GlobalAlias>(DGV)) { 958 // The only valid mappings are: 959 // - SF is external declaration, which is effectively a no-op. 960 // - SF is weak, when we just need to throw SF out. 961 if (!SF->isDeclaration() && !SF->isWeakForLinker()) 962 return Error(Err, "Function-Alias Collision on '" + SF->getName() + 963 "': symbol multiple defined"); 964 } 965 966 // Set calculated linkage 967 DGV->setLinkage(NewLinkage); 968 969 // Make sure to remember this mapping. 970 ValueMap[SF] = ConstantExpr::getBitCast(DGV, SF->getType()); 971 } 972 return false; 973} 974 975// LinkFunctionBody - Copy the source function over into the dest function and 976// fix up references to values. At this point we know that Dest is an external 977// function, and that Src is not. 978static bool LinkFunctionBody(Function *Dest, Function *Src, 979 ValueToValueMapTy &ValueMap, 980 std::string *Err) { 981 assert(Src && Dest && Dest->isDeclaration() && !Src->isDeclaration()); 982 983 // Go through and convert function arguments over, remembering the mapping. 984 Function::arg_iterator DI = Dest->arg_begin(); 985 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 986 I != E; ++I, ++DI) { 987 DI->setName(I->getName()); // Copy the name information over... 988 989 // Add a mapping to our local map 990 ValueMap[I] = DI; 991 } 992 993 // Splice the body of the source function into the dest function. 994 Dest->getBasicBlockList().splice(Dest->end(), Src->getBasicBlockList()); 995 996 // At this point, all of the instructions and values of the function are now 997 // copied over. The only problem is that they are still referencing values in 998 // the Source function as operands. Loop through all of the operands of the 999 // functions and patch them up to point to the local versions... 1000 // 1001 // This is the same as RemapInstruction, except that it avoids remapping 1002 // instruction and basic block operands. 1003 // 1004 for (Function::iterator BB = Dest->begin(), BE = Dest->end(); BB != BE; ++BB) 1005 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) { 1006 // Remap operands. 1007 for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end(); 1008 OI != OE; ++OI) 1009 if (!isa<Instruction>(*OI) && !isa<BasicBlock>(*OI)) 1010 *OI = MapValue(*OI, ValueMap, true); 1011 1012 // Remap attached metadata. 1013 SmallVector<std::pair<unsigned, MDNode *>, 4> MDs; 1014 I->getAllMetadata(MDs); 1015 for (SmallVectorImpl<std::pair<unsigned, MDNode *> >::iterator 1016 MI = MDs.begin(), ME = MDs.end(); MI != ME; ++MI) { 1017 Value *Old = MI->second; 1018 if (!isa<Instruction>(Old) && !isa<BasicBlock>(Old)) { 1019 Value *New = MapValue(Old, ValueMap, true); 1020 if (New != Old) 1021 I->setMetadata(MI->first, cast<MDNode>(New)); 1022 } 1023 } 1024 } 1025 1026 // There is no need to map the arguments anymore. 1027 for (Function::arg_iterator I = Src->arg_begin(), E = Src->arg_end(); 1028 I != E; ++I) 1029 ValueMap.erase(I); 1030 1031 return false; 1032} 1033 1034 1035// LinkFunctionBodies - Link in the function bodies that are defined in the 1036// source module into the DestModule. This consists basically of copying the 1037// function over and fixing up references to values. 1038static bool LinkFunctionBodies(Module *Dest, Module *Src, 1039 ValueToValueMapTy &ValueMap, 1040 std::string *Err) { 1041 1042 // Loop over all of the functions in the src module, mapping them over as we 1043 // go 1044 for (Module::iterator SF = Src->begin(), E = Src->end(); SF != E; ++SF) { 1045 if (!SF->isDeclaration()) { // No body if function is external 1046 Function *DF = dyn_cast<Function>(ValueMap[SF]); // Destination function 1047 1048 // DF not external SF external? 1049 if (DF && DF->isDeclaration()) 1050 // Only provide the function body if there isn't one already. 1051 if (LinkFunctionBody(DF, SF, ValueMap, Err)) 1052 return true; 1053 } 1054 } 1055 return false; 1056} 1057 1058// LinkAppendingVars - If there were any appending global variables, link them 1059// together now. Return true on error. 1060static bool LinkAppendingVars(Module *M, 1061 std::multimap<std::string, GlobalVariable *> &AppendingVars, 1062 std::string *ErrorMsg) { 1063 if (AppendingVars.empty()) return false; // Nothing to do. 1064 1065 // Loop over the multimap of appending vars, processing any variables with the 1066 // same name, forming a new appending global variable with both of the 1067 // initializers merged together, then rewrite references to the old variables 1068 // and delete them. 1069 std::vector<Constant*> Inits; 1070 while (AppendingVars.size() > 1) { 1071 // Get the first two elements in the map... 1072 std::multimap<std::string, 1073 GlobalVariable*>::iterator Second = AppendingVars.begin(), First=Second++; 1074 1075 // If the first two elements are for different names, there is no pair... 1076 // Otherwise there is a pair, so link them together... 1077 if (First->first == Second->first) { 1078 GlobalVariable *G1 = First->second, *G2 = Second->second; 1079 const ArrayType *T1 = cast<ArrayType>(G1->getType()->getElementType()); 1080 const ArrayType *T2 = cast<ArrayType>(G2->getType()->getElementType()); 1081 1082 // Check to see that they two arrays agree on type... 1083 if (T1->getElementType() != T2->getElementType()) 1084 return Error(ErrorMsg, 1085 "Appending variables with different element types need to be linked!"); 1086 if (G1->isConstant() != G2->isConstant()) 1087 return Error(ErrorMsg, 1088 "Appending variables linked with different const'ness!"); 1089 1090 if (G1->getAlignment() != G2->getAlignment()) 1091 return Error(ErrorMsg, 1092 "Appending variables with different alignment need to be linked!"); 1093 1094 if (G1->getVisibility() != G2->getVisibility()) 1095 return Error(ErrorMsg, 1096 "Appending variables with different visibility need to be linked!"); 1097 1098 if (G1->getSection() != G2->getSection()) 1099 return Error(ErrorMsg, 1100 "Appending variables with different section name need to be linked!"); 1101 1102 unsigned NewSize = T1->getNumElements() + T2->getNumElements(); 1103 ArrayType *NewType = ArrayType::get(T1->getElementType(), 1104 NewSize); 1105 1106 G1->setName(""); // Clear G1's name in case of a conflict! 1107 1108 // Create the new global variable... 1109 GlobalVariable *NG = 1110 new GlobalVariable(*M, NewType, G1->isConstant(), G1->getLinkage(), 1111 /*init*/0, First->first, 0, G1->isThreadLocal(), 1112 G1->getType()->getAddressSpace()); 1113 1114 // Propagate alignment, visibility and section info. 1115 CopyGVAttributes(NG, G1); 1116 1117 // Merge the initializer... 1118 Inits.reserve(NewSize); 1119 if (ConstantArray *I = dyn_cast<ConstantArray>(G1->getInitializer())) { 1120 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 1121 Inits.push_back(I->getOperand(i)); 1122 } else { 1123 assert(isa<ConstantAggregateZero>(G1->getInitializer())); 1124 Constant *CV = Constant::getNullValue(T1->getElementType()); 1125 for (unsigned i = 0, e = T1->getNumElements(); i != e; ++i) 1126 Inits.push_back(CV); 1127 } 1128 if (ConstantArray *I = dyn_cast<ConstantArray>(G2->getInitializer())) { 1129 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 1130 Inits.push_back(I->getOperand(i)); 1131 } else { 1132 assert(isa<ConstantAggregateZero>(G2->getInitializer())); 1133 Constant *CV = Constant::getNullValue(T2->getElementType()); 1134 for (unsigned i = 0, e = T2->getNumElements(); i != e; ++i) 1135 Inits.push_back(CV); 1136 } 1137 NG->setInitializer(ConstantArray::get(NewType, Inits)); 1138 Inits.clear(); 1139 1140 // Replace any uses of the two global variables with uses of the new 1141 // global... 1142 1143 // FIXME: This should rewrite simple/straight-forward uses such as 1144 // getelementptr instructions to not use the Cast! 1145 G1->replaceAllUsesWith(ConstantExpr::getBitCast(NG, 1146 G1->getType())); 1147 G2->replaceAllUsesWith(ConstantExpr::getBitCast(NG, 1148 G2->getType())); 1149 1150 // Remove the two globals from the module now... 1151 M->getGlobalList().erase(G1); 1152 M->getGlobalList().erase(G2); 1153 1154 // Put the new global into the AppendingVars map so that we can handle 1155 // linking of more than two vars... 1156 Second->second = NG; 1157 } 1158 AppendingVars.erase(First); 1159 } 1160 1161 return false; 1162} 1163 1164static bool ResolveAliases(Module *Dest) { 1165 for (Module::alias_iterator I = Dest->alias_begin(), E = Dest->alias_end(); 1166 I != E; ++I) 1167 // We can't sue resolveGlobalAlias here because we need to preserve 1168 // bitcasts and GEPs. 1169 if (const Constant *C = I->getAliasee()) { 1170 while (dyn_cast<GlobalAlias>(C)) 1171 C = cast<GlobalAlias>(C)->getAliasee(); 1172 const GlobalValue *GV = dyn_cast<GlobalValue>(C); 1173 if (C != I && !(GV && GV->isDeclaration())) 1174 I->replaceAllUsesWith(const_cast<Constant*>(C)); 1175 } 1176 1177 return false; 1178} 1179 1180// LinkModules - This function links two modules together, with the resulting 1181// left module modified to be the composite of the two input modules. If an 1182// error occurs, true is returned and ErrorMsg (if not null) is set to indicate 1183// the problem. Upon failure, the Dest module could be in a modified state, and 1184// shouldn't be relied on to be consistent. 1185bool 1186Linker::LinkModules(Module *Dest, Module *Src, std::string *ErrorMsg) { 1187 assert(Dest != 0 && "Invalid Destination module"); 1188 assert(Src != 0 && "Invalid Source Module"); 1189 1190 if (Dest->getDataLayout().empty()) { 1191 if (!Src->getDataLayout().empty()) { 1192 Dest->setDataLayout(Src->getDataLayout()); 1193 } else { 1194 std::string DataLayout; 1195 1196 if (Dest->getEndianness() == Module::AnyEndianness) { 1197 if (Src->getEndianness() == Module::BigEndian) 1198 DataLayout.append("E"); 1199 else if (Src->getEndianness() == Module::LittleEndian) 1200 DataLayout.append("e"); 1201 } 1202 1203 if (Dest->getPointerSize() == Module::AnyPointerSize) { 1204 if (Src->getPointerSize() == Module::Pointer64) 1205 DataLayout.append(DataLayout.length() == 0 ? "p:64:64" : "-p:64:64"); 1206 else if (Src->getPointerSize() == Module::Pointer32) 1207 DataLayout.append(DataLayout.length() == 0 ? "p:32:32" : "-p:32:32"); 1208 } 1209 Dest->setDataLayout(DataLayout); 1210 } 1211 } 1212 1213 // Copy the target triple from the source to dest if the dest's is empty. 1214 if (Dest->getTargetTriple().empty() && !Src->getTargetTriple().empty()) 1215 Dest->setTargetTriple(Src->getTargetTriple()); 1216 1217 if (!Src->getDataLayout().empty() && !Dest->getDataLayout().empty() && 1218 Src->getDataLayout() != Dest->getDataLayout()) 1219 errs() << "WARNING: Linking two modules of different data layouts!\n"; 1220 if (!Src->getTargetTriple().empty() && 1221 Dest->getTargetTriple() != Src->getTargetTriple()) 1222 errs() << "WARNING: Linking two modules of different target triples!\n"; 1223 1224 // Append the module inline asm string. 1225 if (!Src->getModuleInlineAsm().empty()) { 1226 if (Dest->getModuleInlineAsm().empty()) 1227 Dest->setModuleInlineAsm(Src->getModuleInlineAsm()); 1228 else 1229 Dest->setModuleInlineAsm(Dest->getModuleInlineAsm()+"\n"+ 1230 Src->getModuleInlineAsm()); 1231 } 1232 1233 // Update the destination module's dependent libraries list with the libraries 1234 // from the source module. There's no opportunity for duplicates here as the 1235 // Module ensures that duplicate insertions are discarded. 1236 for (Module::lib_iterator SI = Src->lib_begin(), SE = Src->lib_end(); 1237 SI != SE; ++SI) 1238 Dest->addLibrary(*SI); 1239 1240 // LinkTypes - Go through the symbol table of the Src module and see if any 1241 // types are named in the src module that are not named in the Dst module. 1242 // Make sure there are no type name conflicts. 1243 if (LinkTypes(Dest, Src, ErrorMsg)) 1244 return true; 1245 1246 // ValueMap - Mapping of values from what they used to be in Src, to what they 1247 // are now in Dest. ValueToValueMapTy is a ValueMap, which involves some 1248 // overhead due to the use of Value handles which the Linker doesn't actually 1249 // need, but this allows us to reuse the ValueMapper code. 1250 ValueToValueMapTy ValueMap; 1251 1252 // AppendingVars - Keep track of global variables in the destination module 1253 // with appending linkage. After the module is linked together, they are 1254 // appended and the module is rewritten. 1255 std::multimap<std::string, GlobalVariable *> AppendingVars; 1256 for (Module::global_iterator I = Dest->global_begin(), E = Dest->global_end(); 1257 I != E; ++I) { 1258 // Add all of the appending globals already in the Dest module to 1259 // AppendingVars. 1260 if (I->hasAppendingLinkage()) 1261 AppendingVars.insert(std::make_pair(I->getName(), I)); 1262 } 1263 1264 // Insert all of the globals in src into the Dest module... without linking 1265 // initializers (which could refer to functions not yet mapped over). 1266 if (LinkGlobals(Dest, Src, ValueMap, AppendingVars, ErrorMsg)) 1267 return true; 1268 1269 // Link the functions together between the two modules, without doing function 1270 // bodies... this just adds external function prototypes to the Dest 1271 // function... We do this so that when we begin processing function bodies, 1272 // all of the global values that may be referenced are available in our 1273 // ValueMap. 1274 if (LinkFunctionProtos(Dest, Src, ValueMap, ErrorMsg)) 1275 return true; 1276 1277 // If there were any alias, link them now. We really need to do this now, 1278 // because all of the aliases that may be referenced need to be available in 1279 // ValueMap 1280 if (LinkAlias(Dest, Src, ValueMap, ErrorMsg)) return true; 1281 1282 // Update the initializers in the Dest module now that all globals that may 1283 // be referenced are in Dest. 1284 if (LinkGlobalInits(Dest, Src, ValueMap, ErrorMsg)) return true; 1285 1286 // Link in the function bodies that are defined in the source module into the 1287 // DestModule. This consists basically of copying the function over and 1288 // fixing up references to values. 1289 if (LinkFunctionBodies(Dest, Src, ValueMap, ErrorMsg)) return true; 1290 1291 // If there were any appending global variables, link them together now. 1292 if (LinkAppendingVars(Dest, AppendingVars, ErrorMsg)) return true; 1293 1294 // Resolve all uses of aliases with aliasees 1295 if (ResolveAliases(Dest)) return true; 1296 1297 // Remap all of the named mdnoes in Src into the Dest module. We do this 1298 // after linking GlobalValues so that MDNodes that reference GlobalValues 1299 // are properly remapped. 1300 LinkNamedMDNodes(Dest, Src, ValueMap); 1301 1302 // If the source library's module id is in the dependent library list of the 1303 // destination library, remove it since that module is now linked in. 1304 sys::Path modId; 1305 modId.set(Src->getModuleIdentifier()); 1306 if (!modId.isEmpty()) 1307 Dest->removeLibrary(modId.getBasename()); 1308 1309 return false; 1310} 1311 1312// vim: sw=2 1313